1. Technical Field
The present invention relates to a method for mounting multishaft servo-amplifier modules on a multishaft servo-amplifier for driving motors used in an industrial machine.
2. Background Art
Conventionally, for simultaneously controlling a plurality of motors by a host controller, the connection between the host controller and a servo-amplifier for driving respective shafts is electrically provided through bus connection, serial communication or the like using a communication interface device which is connected to a transmission cable (see JP-A-2002-140103, for example).
FIG. 9(a) and FIG. 9(b) are block diagrams showing configuration examples of the multishaft servo-amplifier used in the above case. FIG. 9(a) shows Configuration Example 1 and FIG. 9(b) shows Configuration Example 2 of the multishaft servo-amplifier. In FIGS. 9(a) and 9(b), reference number 83 designates a host controller, reference numbers 84 designate communication interfaces, reference numbers 85 designate multishaft servo-amplifier modules, reference number 86 designate servo-motors, reference number 87 designates a transmission cable, reference number 88 designate bus connections or serial communication or the like, reference number 89 designate motor cables, and reference number 90 designate a multishaft servo-amplifier function unit 90.
As illustrated in these figures, for controlling a plurality of servo-amplifiers, the host controller 83 is typically connected to the communication interfaces 84 through the transmission cable 87. The communication interfaces 84 are further connected to the multishaft servo-amplifier modules 85 through the bus connection, the serial communication or the like 88.
FIG. 9(a) shows the example where the communication interfaces 84 and the servo-amplifier modules 85 are arranged with a one-to-one correspondence. FIG. 9(b) shows the example where one communication interface 84 is provided for the plural servo-amplifier modules 85 with a one-to-N (plural) correspondence.
In both of the examples, the plural multishaft servo-amplifier modules are often collectively disposed in a side-by-side arrangement together with the communication interface(s) for reasons of limitation to a supply line or the like of a power source and to wiring or for other reasons.
An area boxed by a dotted line is the multishaft servo-amplifier function unit 90 including plural multishaft servo-amplifier modules disposed side by side. Each of the mutishaft servo-amplifier modules 85 is connected to the corresponding servo-motor 86 through the motor cable 89.
A typical mechanical method for providing a side-by-side arrangement of the multishaft servo-amplifier function unit 90 as the multishaft servo-amplifier involves a base-mounted type where the multishaft servo-amplifier modules are mounted on a base plate for installation, a rack-mounted type where the multishaft servo-amplifier modules are mounted on a rack, and the like.
An example of the method for mounting the multishaft servo-amplifier modules is described herein referring to the appended drawing. FIG. 10 is an isometric drawing illustrating an example of an entire structure of a multishaft servo-amplifier on which base-mounted type multishaft servo-amplifier modules are mounted by a conventional method.
The multishaft servo-amplifier shown in the figure includes one communication interface and six multishaft servo-amplifier modules, thereby constituting a six-shaft servo-amplifier which controls six servo-motors by the entire structure.
This multishaft servo-amplifier corresponds to the multishaft servo-amplifier function unit 90 shown in FIG. 9(b), where one communication interface 92 and six multishaft servo-amplifier modules 93 are mounted on a base plate 91.
Each of the multishaft servo-amplifier modules 93 has a case 102, and a printed board 103 which is equipped with semiconductor power elements and electronic parts generally required for a servo-amplifier.
Connectors 96 and 97 disposed on each of the multishaft servo-amplifier modules 93 electrically connects to a motor or an encoder, or electrically supplies power, control signals, signal inputs/outputs, transmission and the like. The connectors 96 and 97 are mounted on the printed board 103.
Connectors 94 and 95 disposed on the communication interface 92 electrically supplies power, control signals, signal inputs/outputs, transmission and the like. The connectors 94 and 95 are connected with the host controller through the transmission cable.
The communication interface 92 and the multishaft servo-amplifier modules 93 are electrically connected to each other through bus connection, serial communication or the like, which is omitted in the figure.
As for mechanical connections relating to the present invention, the printed boards 103 of the six multishaft servo-amplifier modules 93 are mounted on the base plate 91, which has a sufficient area and strength for mounting the plural multishaft servo-amplifier modules 93, in such positions as to be disposed perpendicularly to the flat surface of the base plate 91. Each of the multishaft servo-amplifier modules 93 is fixed to the base plate 91 by screws 101 having a length appropriate for fixation therebetween, which screws are inserted into two multishaft servo-amplifier module fixing plate upper holes and two multishaft servo-amplifier module fixing plate lower holes 100 provided on upper and lower multishaft servo-amplifier module fixing plates 99, respectively, and are inserted into four multishaft servo-amplifier module attachment screw taps 98 provided on the base plate 91 in correspondence with the upper and lower holes 100.
As described above, in the conventional base-mounted type servo-amplifier for a host controller, the plural multishaft servo-amplifier modules are mounted on the base plate perpendicularly thereto. These multishaft servo-modules simultaneously control the corresponding plural servo-motors.
In recent years, there has been an increasing need for space-saving installation of a multishaft servo-amplifier. Furthermore, the number of shafts tends to be increased due to enlarged functions in the field of industrial machinery including semiconductor manufacturing apparatus such as a chip mounter. Additionally, the demand for mounting the multishaft servo-amplifier itself on a movable part of a machine has been increasing for the reason of wiring-saving or other reasons.
Accordingly, it is preferable that the multishaft servo-amplifier used in this field is not only small-sized and light-weight but also has high mechanical rigidity and a thin structure for increasing resistance to vibration and shock and for decreasing inertia generated at the time of high-speed motion in the mechanical structure aspects.
In the conventional method, however, the servo-amplifier modules are mounted on the surface of the base plate perpendicularly thereto. As a result, the depth of the multishaft servo-amplifier in the thickness direction of the base plate is large and it is thus impossible to install the multishaft servo-amplifier in a narrow space having a small depth.
Additionally, when the multishaft servo-amplifier is carried on a movable part of a machine, the entire thickness of the multishaft servo-amplifier is large for the carrying surface of the machine. Since the resistance to vibration and shock and the mechanical rigidity are decreased due to the large thickness of the servo-amplifier, it is difficult to mount the servo-amplifier on the movable part of the machine which is required to move at high speed.